Question: Is dyslexia a hereditary dissorder? Are their any external influences that have an effect on whether someone develops dyslexia and if so what are the preventative measures that can be undertaken by an individual?

As far as I know, we don’t really know yet. It certainly seems to run in families, but whether this is genes or environment, we don’t know.
I also don’t know if there is anything you can do to prevent it, but there are strategies or ways of coping that people can use to try and deal with their dyslexia. This includes lots of educational support, reducing anxiety and stress and intervening early gives the greatest amount of help for people.

Yes, there certainly seems to be genetic components that predispose to dyslexia, but this isn’t the whole story. It’s not as simple as a single gene, but we’re learning more and more about this. Quite similar to the situation with autism actually.